ELI5: Why can small insects like ants fall many times their height and come out uninjured but larger animals like humans are easily hurt?

Ants can drop or be flung hundreds of times their height, but a human can only fall at most three or four times their height without being hurt. Specifically, what about the exoskeleton of an insect makes it so tough? Why didn't larger animals evolve to have the same ability?

Essentially, ants are tiny so their terminal velocity is really low. A low terminal velocity plus a tiny mass mean that there's not a lot of force built up when the ant hits the ground.

Edit: Forgot a few questions you asked. Larger animals don't have exoskeletons because they would have to be impossibly thick to sustain greater body weights thanks to the square cube law (When you increase your size by 2, the cross sectional area of your leg support would increase by 4, but the weight it supports would increase by 8.) You would basically be doubling the stresses on your exoskeleton each time you doubled in size.